The present invention relates to a knife-edge type bearing system.
In general, the conventional knife-edge type bearings comprise a knife-edge member, a bearing member adapted for making line contact with the edge of the knife-edge member for pivotal movement thereof, and side plates positioned on both sides of the bearing member for preventing the displacement in the longitudinal direction of the knife-edge member. Pointed edges are extended from both ends of the knife-edge member and are brought into contact with the side plates with a minimum contact area for permitting the smooth pivotal movement of the knife-edge member.
The conventional knife-edge bearings with the above construction are objectionable for the following reasons:
A. In general, the knife-edge bearings are used in, for instance, a balance where a nearly frictionless bearing must be provided. But the pointed edges extended out of the ends of the knife-edge member are brought into contact with the side plates so that the inevitable friction losses occur between them even when the area of contact between them is minimized; and
B. In order to minimize wear, the knife-edge member is, in general, made of a jewel such as rubby, sapphire, agate, etc. or hardened steel, but the pointed-edges tend very frequently to be broken under the external impacts resulting in the increase in frictional force between the pointed edges and the side plates.
A knife-edge bearing without side plates may be conceived, but cannot be successfully used in practice because of the free displacement in the longitudinal direction of the knife-edge member.